GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"16162 results found.
- ZTF23aaoohpy/AT2023lcr: LBT observations
- GRB230628E: VLT optical identification of afterglow candidate
- GRB 230628E: LCOGT Optical Upper Limit
- LIGO/Virgo/KAGRA S230516az: GOTO candidate counterpart GOTO23hu ruled out by Zwicky Transient Facility observations
- ZTF23aaoohpy /AT2023lcr: TNG NIR detection
- LIGO/Virgo/KAGRA S230627c: ATLAS information on the ZTF candidates
- ZTF23aaoohpy/AT2023lcr: further SAO RAS observations
- ATLAS23msn/ZTF23aaoohpy/AT2023lcr: Zeiss-1000 of Koshka observatory optical observations
- MAXI GRB 230623A: MASTER optical observations
- ZTF23aaoohpy/AT2023lcr: SAO RAS observations
- AT2023lcr: VLA radio detection
- ZTF23aaoohpy/AT2023lcr: Montarrenti Observatory optical observations
- ZTF23aaoohpy (AT2023lcr/ATLAS23msn): Swift/UVOT detection
- ZTF23aaoohpy/AT2023lc: Mondy optical observations
- AT2023lcr: Neil Gehrels Swift Observatory X-ray detection
- ZTF23aaoohpy/AT2023lcr: Keck/LRIS spectroscopy and redshift
- ZTF23aaoohpy/AT2023lcr: Xinglong-2.16m optical observations
- ZTF23aaoohpy/AT2023lcr: Liverpool Telescope detection
- ZTF23aaoohpy/AT2023lcr: OHP/T193 and OHP/T120 optical follow-up observations
- ZTF23aaoohpy/AT2023lcr: GOTO early optical observations and constraint
- GRB 230618A: Swift/UVOT Upper Limits
- GRB 230618A: KAIT Optical Observations
- GRB230618A: LCOGT Optical Observations
- LIGO/Virgo/KAGRA S230615az: T80S Search and Candidate Counterpart Identification
- LIGO/Virgo/KAGRA S230615az: Non-Detections of GROWTH-India Candidates from GECKO Optical Observations
- LIGO/Virgo/KAGRA S230615az: GOTO candidate counterparts
- GRB 230606A: LCOGT Optical Observations
- ZTF23aamxeqf/AT2023jxk: 1.3m DFOT Optical upper limit
- ZTF and GIT Observations of the Candidate Optical Afterglow AT2023jxk
- GRB 230606A: Gaoyazi/GOT optical upper limit
- GRB 230606A: BOOTES-5/JGT optical upper limit
- GRB 230606A: Swift/UVOT Upper Limits
- LIGO/Virgo/KAGRA S230518h: TESS observations of the localization region
- LIGO/Virgo/KAGRA S230521k: MASTER new OT discovery
- LIGO/Virgo/KAGRA S230521k: Additional candidates from Zwicky Transient Facility
- LIGO/Virgo/KAGRA S230518h: ATCA follow-up of candidate counterparts
- LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
- LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
- LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
- Improved IPN triangulation of GRB 230512A
- GRB 230512A: Nanshan/NEXT non-detection of GRB afterglow candidate
- GRB 230512A: Liverpool Telescope observations
- GRB 230512A: GIT non detection of afterglow candidate
- GRB 230512A: Kitab possible afterglow candidate
- GRB 230510A: OHP/T193 and OHP/T120 optical observations
- GRB 230512A: GIT optical follow-up ZTF candidates
- GRB 230510A: GIT optical upper limits
- GRB 230510A: LCOGT Optical Upper Limit
- GRB 230510A: Gaoyazi/GOT optical upper limit
- GRB 230510A: Nanshan/NEXT optical afterglow detection
- GRB 230506B: Swift/UVOT further analysis
- GRB 230506C: SAO RAS optical observations
- GRB 230307A: JWST second-epoch observations
- GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
- GRB 230506B: LCOGT Optical Upper Limits
- GRB 230506C: Swift/UVOT Upper Limits
- GRB 230506C: NUTTelA-TAO / BSTI Early Optical Limits
- GRB 230506B: MASTER optical observations
- GRB 230420A: Mondy optical afterglow detection, TSHAO, CrAO optical upper limit
- GRB 230420A: AROMA-N Optical Upper Limit
- GRB 230427A: NOT optical upper limit
- GRB 230427A: TSHAO, SAO RAS, AbAO optical upper limit
- GRB 230427A: Gaoyazi/GOT optical upper limit
- GRB 230427A: Nanshan/HMT optical upper limit
- GRB 230427A: Osservatorio Astronomico Nastro verde upper limit
- GRB 230427A: GIT optical upper limit
- GRB 230427A: Bassano Bresciano Observatory upper limit
- GRB 230427A: GMG upper limit
- GRB 230427A : OHP/T193 optical upper limit
- GRB 230427A: BOOTES-5/JGT afterglow detection
- GRB 230426A: MASTER OT J023135.16-792104.8 optical counterpart discovery
- GRB 230427A: MITSuME Akeno optical upper limits
- GRB 230427A: Swift detection of a burst with an optical counterpart
- GRB 230423A: Swift/UVOT Upper Limits
- GRB 230420A: Lowell Discovery Telescope Optical Detection
- GRB 230420A: Swift/UVOT Upper Limits
- GRB230420A: VLT optical observation
- GRB 230420A: MITSuME Akeno optical observation
- GRB 230420A: NOT optical afterglow confirmation
- GRB 230420A: Gaoyazi/GOT optical upper limit
- GRB 230420A: BOOTES-5/JGT optical afterglow detection
- GRB 230420A: LCOGT Optical Upper Limit
- GRB230414B: VIRT Optical Upper Limit
- GRB 230414B: Nickel and KAIT telescope optical observations
- GRB 230414B: Swift/UVOT Detection
- GRB 230414B: Osservatorio Astronomico Nastro Verde - Sorrento: optical observations
- VIRT optical transient detection
- GRB 230414B: 3.6m DOT Optical observations, slow decay at early epochs
- GRB 230307A: iTelescope optical upper limit (likely)
- GRB 230414B: Montarrenti Observatory late time optical afterglow detection
- GRB 230414B: Lulin 40cm-SLT optical limit
- GRB 230414B: Bassano Bresciano Observatory optical observations
- GRB 230414B: AbAO optical observations
- GRB 230409B: 3.6m DOT near-infrared detection, afterglow confirmation
- GRB 230414B: Dabancheng/GHOST optical observations
- GRB 230414B: slow optical light curve decay
- GRB 230414B: SAO RAS optical observations
- GRB 230414B: 1.3m DFOT Optical observations
- GRB 230414B (correction GRB name in the GCN 33615): Mondy optical afterglow candidate
- GRB 230414B: Nanshan/HMT optical afterglow detection